Automatic braking mechanism



Dec. 22, 1931. R. Nr-:uscHoTz AUTOMATIC BRAKING MECHANISM Filed Sept. 5, 1929 E INVENTOR Patented Dec. 22, 1931 STATES Y ROBERT NnUsoHoTz,

or NEW Yoizx, N. Y.

AUTOMATIC Bnnxiive MncHAnIsM Application led September la# therewith by means of a wedge member operated as the result of rotation of a drum by a. speed governed cable. Such a mechanism is satisfactory to some degree for stopping an elevator when the same is fully loaded since the weight oi` momentum of the elevator causes the jaws-to slide along the guide rail beforeiirmly gripping the same. However, when the car is loaded otherwise than full load, the action of the jaws upon excessive speed of the elevator isl to stop the same so suddenly as to endanger occupants of the car. This is due to the factthatthe weight in the car causes its momentum to be decreased an amount suihcient vto permit the aws to lock along the guide rail and stop the car too sud-iy denly.

An object of the present inventionis to pron vide improved braking mechanism for automatic operation upon excessive speed of an elevator. v l 'y Another objectA of the invention is to provide' braking mechanism for elevators with devices for compensating' for variation in load of the elevator.

In accordance with the present invention, use is made of a pair of Jaws sliding along one of the guide rails which `yaws are forced into contact with the rail by means of the` usual wedge. Y vthe closing` ofthe jaws positive due to the However, instead of making wedge, one of the jaws is so arranged as to permit it to slide along the rail without actually locking thereagainst. A tension device is 5, 1929. seriai No. 390,482.

on the counterweight frame, thereby precluding excess speed of the elevator in an upward direction. y

Other objects and features of the invention will become evidentY by Vconsideration of the following detailed description taken in connection with the accompanying drawingswherein Y Y Fig. 1 is a side elevation of the mechanism employed in the present invention.

Fig. 2 is a section taken on the'lines 24-2 of Fig. 1, and

Fig. 3 is a section taken on the lines 3-3' of Fig. l.

`Referring now cates the frame members comprising the sling ofthe elevator car which sling is lslidable along the usual guide rails 11, one of which is-illustrated herein. As is usual in elevator constructions, a cable 12 is so mounted as to move concurrently with the car, its move'- inent being between a pair of cam-like rollers 13 which are governed by automatic governing mechanism not illustrated herein'V and forming no part of the present invention. 1

Secured to cable 12in any desired manner is a cable 111 passing around idler rollers 15 aflixed tothe elevator car proper and wound upon a drumv 16 mounted beneath'the sling of the car. Drum 16 is rigidly secured to a f collar 17 whichv collar is mounted for rotation in bearing'members 18, one of which is illustrated herein. The collar 17 is internally threaded for the reception of a rod 19 one end of which is formed in the shape of a wedge 20. i

Mounted beneath the sling of the carfor pivotal movement isfa member 21 having a j aw 22-adapted to engage one side of the guide rail 11 and at the other end a wedge follower 23 contacting with wedge 20. Oppositely.

mounting therein of a threaded bar 27.v The pivotal portion of member 24 is in substantial Lshape upon shaft 28 and pivot-allymounted on this shaft between the parts comprising the L-shaped portion is a member 29 having a wedge follower 30 at the free end thereof.

to the drawings, 10 indi-l Rigidly secured to the threaded bar 27 in any desired manner is an arm 31 having adjustably secured thereto a weight 32. This arm 31 is normally held in a desired position through the agency of a spring 33. The arm 31 is connected by a link 34 with a head 38 on the end of a rod 36 around which the spring 33 is positioned. This rod 36 as shown passes through a flange 37 secured to the channel bar 10 which forms a part of the saddle of the car. The tension of the-spring V33 may Abe adjusted by manipulation of nuts threaded on the end of rod 36 and working against a washer 39 which is directly in contact with one end of the spring, the other end of which rests against the top of flange 37.

.As will be seen clearly in Fig.- 2, one end of threaded rod 27 rests against the member 29 yso that movement 0f this member due to movement of the wedge will be transmitted to the member 2 4 which has as a part thereof the jaw 25.

The operation of the braking mechanismsv is substantially. as follows. :Let it be assumed that the car is fully loaded'for which condition-the spring 33 is so adjusted and the weight 32 so positioned that stopping of the car within the selected distance will have no effect thereon. Under these conditions let it be further assumedlthat the elevator exceeds its maximum speed. The governing mechanism (not. shown) will cause the camrollers 13 to be moved, grippingthe cable 12 which moves concurrently' with the car. This gripping motion arrests movement of cable 12 and as a result continued movement ofthe car causes the unwinding of cable 14 from drum lf3-thereby rotating this drum. Rotation of the drum 16 causes thewedge 20 to be moved in a y*direction away from the guide rail 11 forcing the wedge followers 23 and 30out wardly. .This movement of the wedge followers is transmitted in one instance directly to jaw 22 and in the other instance through vthe rod 27 to aw 25. lThe weight of the `car and the momentum thereof under full load will cause the jaws 22 and 25 to slide along the rail a short distance until further rotation of drum 16 causes them through the agency of wedge 20to be firmly locked against the rail. Under these normal conditions the locking of the jaws will take place within the selected distance approved by safety factors. In the operation just described, the arm 31 is inactive due to tension on spring 33 thereby holding rod 27 against rotation and permitting the jaw 25 to be locked without interference. i'

Let 'itnow be assumed that the car is very lightly loaded. Vhen it exceeds its maximum speed the cable 12 as before is locked against movement, unwinding cable 14 and rotating-drum `16. This movement of drum 16-holds the wedge 20 between the followers `23 and'30 and forces jaws 22 and/25.

against the guide rail. Since the weight of the car is reduced and consequently the momentum thereof is less, the normal tendency would be for the aws to lock quickly against the rail, stopping the car almost immediately. However, when the car starts its rapid stopping the weight 32 swings the arm 31 downwardly causing a slight rotation of bar 27, moving it a fractional distance from member 29 and thereby relieving tension on the aw 25. i Continued movement of wedge 20 tightens the member 29 against the 'end of the rod 27 again applying pressure to force jaw 25 against the rail l11. If this stopping is still too suddenly applied, the weight 32 due to its momentum will further release rod 27 easing up on the gripping of jaw 25. As soon as the stopping of the car has reached normal operation, the spring 33 will prevent further movement of arm 31 and accordingly the two jaws willA be locked against the rail.

It is to be understood that the apparatus will function by causing each aw to be yieldable as well as by causing one as illustrated. If so desired separate weights may be utilized in connection with each jaw for securing this yieldable gripping or a single weight may be utilized for both jaws. Or there may be a pair of jaws on each side of the elevator with lever connections from each of said pairs operating with a common weight. It should be borne in mind, for the purposes of this invention, that it makes no difference whether the inertia weight is connected to one of a pair of jaws or both jaws of a pair, or whether it is connected to more than one pair of such jaws, as such changes would all come under the heading of slightly different embodiments of this invention apparent to anyone skilled in such work.

From the foregoing it will be seen that the present invention provides mechanism whereby an elevator will be automatically stopped within a selected distance under any condition of load thereof. It will be understood of course that the weight 32 will be of such size and so positioned on arm 31 and the tension of spring 33 will be so adjusted that under normal load conditions the jaws will be locked without interference or without easing up on pressure by rotation of rod 27. Whenever the car is lightly loaded and is stopped too suddenly the momentum transmitted to weight 32 is sufficient to depress arm 31, easing the tension on one of the jaws and thereby permitting the stopping of the car to be gradual instead' of abrupt.

It will be seen that the present invention provides mechanism whereby the factor of safety in stopping cars automatically under type loaded car so that the stopping of the Car in any instance will be gradual and distributed over the selected distance along the guide rail. It is to be understood that the invention is not to be limited to the illustrated embodiment but is to be limited only j by the scope of the following claims.

I- claim; n

l. Apparatus of the character described comprising means attached to a moving frame for gripping contact with a stationary object, means for applying pressure to grip said first means upon excessive speed of said moving frame and means for relieving the pressure a slight amount upon stopping of the moving frame more abrupt than the predetermined maximum.

2. Apparatus of the'character described comprising a pair ofjaws attached to an elevator and traveling adjacent a stationary 0bject, means operable upon excessive speed of said elevator to apply pressure forcing said jaws into engagement with said object to stop the elevator and means for relieving the pressure on said jaws when the stopping of the elevator exceeds the predetermined abruptness. f

3. Apparatus of the character described comprising a pair of jaws attached to an elevator and traveling therewith adj lacentl to a stationary object, means for exerting pressure to lock'said jaws to said object upon excessive speed of the elevator to stop the same and means interposed between one of said jaws and the pressure applying means causing release of said jaw upon excessively abrupt stopping of the elevator.

4. Apparatus of the character described comprising gripping jaws attached to an elevator for contact with a stationary object, a wedge member for operating said grippin .f.r

- jaws and inertia means co-operating with said jaws to stop said elevator within substantially the same distance of travel for all load conditions when said elevator exceeds predetermined maximum speed.

5. In a device of the character described, an elevator having safety jaws adapted to grip a safety rail, a wedge to force said jaws into engagement with said rail, and a weight connected to one of said jaws so that movement of the Weight relative to the jaw changes the distance from the central axis of the wedge to the point of force applica tion of said jaw.

6. In a device of the character described, an elevator having safety jaws adapted to grip a safety rail, a wedge to force said jaws into gripping contact with said rail, and a levered weight screw-connected to one of said jaws so that movement of the weight up or down relative to the jaw changes the distance from the central axis of the wedge to the first point of force application on said jaw.

7. In a device of the character described,

" an elevator having safety jaws adapted to 

